Managing Weed Problems in Kentuckys Pastures and Hayfields J.D. Green, Ph.D. Extension Weed Science

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Managing Weed Problems in Kentuckys Pastures
and HayfieldsJ.D. Green, Ph.D.Extension Weed
Science Specialist Department of Plant Soil
SciencesUniversity of Kentucky
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Issues Which Limit Herbicide Use in
Pastures/Hayfields

• Forages interseeded with legumes (eg. Clover)
• Timing of effective treatment
• Other crops have higher priority
• Failure to recognize the problem until after the
  fact
• Sensitive crops growing nearby
• Tobacco, Vegetable Crops, Grapes
• Rural Home Sites (ornamentals, home gardens)
• Grazing Restrictions
• Cost of Treatment

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Herbicides Labeled for Broadleaf Weed Control in
Grass Pastures - Kentucky

• 2,4-D various
• Clarity / Banvel dicamba
• Overdrive dicamba diflufenzopyr
• WeedMaster / Outlaw dicamba 2,4-D
• Crossbow triclopyr 2,4-D
• Redeem RP triclopyr clopyralid
• Remedy / Pathfinder II triclopyr
• Pasturegard triclopyr fluroxypyr
• Milestone aminopyralid
• Cimarron / Ally metsulfuron
• Cimarron Max metsulfurondicamba2,4
  -D

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Pasture Herbicides Not Available in Kentucky

• Surmount 1 picloram fluroxypyr
• Grazon PD 1 picloram 2,4-D
• 1 Restricted Use Pesticide

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PastureGard(triclopyr fluoxypyr)

• Control of unwanted woody plants and herbaceous
  broadleaf weeds
• eg. blackberry, locust, multiflora rose, osage
  orange
• Application rate
• Broadcast - 3 to 8 pt/A
• High Volume Spray 1 to 2 gal/100 gal
• Add surfactant (1 to 2 v/v)
• Grazing and Haying Restriction
• No grazing restrictions, except lactating dairy
  animals
• Lactating Dairy Do not graze or harvest green
  forage for lactating dairy animals from treated
  areas during the same growing season
• Do not harvest hay within 14 days

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Milestone(aminopyralid)

• Herbaceous broadleaf weeds
• Including biennial thistles, Canada thistle, tall
  ironweed
• Application rate
• Broadcast - 5 to 7 oz/A
• Add surfactant (0.25 to 0.5 v/v)
• Grazing and Haying Restriction
• No restrictions following application
• Do not transfer animals from treated areas
  without first allowing 3 days of grazing on
  untreated pasture
• Do not spread manure, hay, or straw if animals
  have grazed within the previous 3 days on treated
  areas

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Tall Ironweed Management

• Mow pastures in mid- to late-summer
• Allow tall ironweed to develop vegetative
  regrowth (12 to 20 tall)
• Spray herbicide in the fall (early September)

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Tall Ironweed Herbicides

• Crossbow triclopyr 2,4-D
• Redeem RP triclopyr clopyralid
• Pasturegard triclopyr fluroxypyr
• Milestone aminopyralid

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Roundup Ready Alfalfa

• Broad spectrum control of weedy grasses and
  broadleaves
• Apply from emergence until 5 days prior to
  cutting
• Application rate
• eg. Roundup WeatherMAX 22 to 44 oz/A
• Do not exceed 44 oz/A per application
• Sequential applications at least 7 days apart
• Grazing or hay cutting restrictions
• Remove livestock before treatment
• Wait a minimum 5 days after application

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Economic Cost vs Benefit

• Value of the Crop
• Cost of seed (including technolgy fees)
• Treatment Cost
• (herbicide application fees)
• Impact if left untreated
• forage quantity
• forage quality
• harvestability

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Roundup Ready Alfalfa

• During Stand Establishment
• Up to 10 of seedlings may not contain the
  RR-gene
• Recommended to apply Roundup at or before 3 to 4
  trifoliate growth stage
• Newly Seeded and Established Stands
• Apply after weeds have emerged, but before
  alfalfa growth or re-growth interferes with
  application spray coverage

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Forage Crop Weed Control

• Website addresses
• Pasture Weed Control Guide (AGR-172)
• http//www.ca.uky.edu/agc/pubs/agr/agr172/agr172.p
  df
• Buttercup Control
• http//www.uky.edu/Agriculture/Agronomy/Weeds/
• Tall Ironweed Control
• http//www.uky.edu/Agriculture/Agronomy/Weeds/
• Alfalfa / Legume Weed Control Guide (AGR-148)
• http//www.ca.uky.edu/agc/pubs/agr/agr148/AGR148.P
  DF